It seems unusual that the App Store is requiring another debit card. Here’s what you can try:
1. Check if your card details are correct: Go to Settings > [Your Name] > Payment & Shipping. Make sure the details are correct.
2. Try another payment method: Even though you said you don’t want to add another card, this is just to see if the issue is with the specific card or with your Apple ID. You can remove this card later.
3. Sign out and sign back in to your Apple ID: Go to Settings > [Your Name] and scroll down and tap “Sign Out”. After signing out, sign back in and see if the issue persists.
4. Contact Apple Support: If all else fails, contact Apple Support directly. They have more tools to investigate and can assist further.
Remember, don’t share sensitive information like your password or credit card details unless you’re sure you’re on a secure Apple site.